The present invention provides an ex vivo method for aiding the diagnosis of Alzheimer's disease in a patient comprising: (i) determining the number of alleles of ApoE4 in the patient's genome; (ii) determining the combined expression level of at least three platelet proteins in a platelet sample from the patient; and (iii) comparing the resulting value of step (ii) to a control value, wherein the at least three platelet proteins include at least one isoform of alpha-tropomyosin containing exon 1a and at least two platelet proteins selected from monoamine oxidase-B, coagulation factor XIIIa, wild-type GSTO-1 or mutant GSTO-1, wherein a result higher than the control value is indicative of Alzheimer's disease.The invention also provides a solid support comprising one or more ligands of at least one isoform of alpha-tropomyosin containing exon 1a, and one or more ligands of at least two platelet proteins selected from monoamine oxidase-B, coagulation factor XIIIa, wild-type GSTO-1 protein and/or mutant GSTO-1 protein immobilized thereon.